Spring and shackle connector



Feb. 27, 1962 A. F. BILLARD SPRING AND SHACKLE CONNECTOR 3 Sheets-Sheet 1 Filed March 5, 1960 INVENTOR. W ;%M 4)g Feb. 27, 1962 A. F. BILLARD SPRING AND SHACKLE CONNECTOR 3 Sheets-Sheet 2 Filed March 3, 1960 FIG.9

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Feb. 27, 1962 A. F. BILLARD SPRING AND SHACKLE CONNECTOR 3 Sheets-Sheet 3 Filed March 3, 1960 FIG.I6

Compression 3 Rebound F I G. I?

O O W H 9 5 8a nJ 5 20m Inches Flat Spring m; M 7 M% 7 United States Patent 3,022,991 SPRING AND SHACKLE CGNNECTOR Anthony F. Biilard, Mansfield, Pa. (32 Dogwood Lane, Tenaily, NJ.) Filed Mar. 3, 1969, Ser. No. 12,624 8 Claims. (Cl. 26754) This invention relates to automobile rear end spring suspensions which include a leaf spring having an eye at one end pivotally connected by a pin to the car frame and an eye at the other connected to the frame by a shackly commonly made of a pair of spaced parallel plates secured together by a pair of bolts. More particularly, the invention is concerned with a spring suspension of the type referred to which includes a novel device for connecting one eye of the spring to the bolt at one end of the shackle. The use of the new connector causes a change in the angle of the shackle in relation to the spring with the result that the characteristics of the sprin are altered and the spring is made capable of carrying overloads in safety. A vehicle having spring suspensions equipped with the new connectors has increased stability under full load or an overload on smooth and rough roads and in taking curves and sufiers little or no deterioration in ride when only lightly loaded.

In automobile rear end suspensions including a leaf spring and a shackle connected to the spring by one bolt, the other shackle bolt is disposed either in an opening in the car frame or in an eye at one end of a hanger connected to the frame and extending to a point below the spring. A shackle of the first kind is under compression in use, while a shackle of the second kind is under tension. In either case, the spring stillness at the design height of the car body and with the spring approximately flat depends upon the shackle angle, which is the angle between a line passing through the axes of the shackle bolts and a line passing through the centers of the spring eyes. The design height is'the position of the body or frame in relation to the axle when the car is under design load corresponding to the weight of a selected number of passengers, such as five, of an average weight of 150 lbs. each, and the normal shackle angle is the shackle angle when the car is under design load. -When the spring is fiat and the distance between the spring eyes is greatest, the spring is said to be at zero geometric deflection and the spring is usually in this position at design load, although the design load position of the spring may be slightly above or below the flat position.

In ordinary production passenger cars with compression shackles, the shackle angle is usually approximately 70, when the car is under design load, and the average spring stiffness or rate is about 112 lbs. per in. Reducing the shackle angle at design height increases the average spring stitfness and, with a shackle angle of 40, the average spring stiffness or rate is about 140 lbs. per in. The shackle angle of a tension shackle in production cars is also usually about 70, when the car is under design load, and the average spring stillness is about 87.5 lbs. per in. With a tension shackle, an increase in the shackle angle increases the spring stiffness until, with an angle of 110, the stiffness is about 112.5 lbs. per in.

The shackle connector of the invention is constructed to take advantage of the change in spring characteristics from the changes in shackle angles 'set forth above and, when employed with a conventional spring and shackle, the connector changes the shackle angle to increase the spring stiffness. The effect of using the connector is thus somewhat the same as changing the shackle angle by changing the spring length, although the effect of 3,2Z,9l latented Feb. 27, 1962 a change in spring length alone on spring stiffness is so small in comparison to the effect of a change in shackle angle as to be negligible.

For a better understanding of the invention reference may be made to the accompanying drawings, in which FIG. 1 is a view in side elevation with parts broken away of an automobile rear spring suspension including a tension shackle and the new connector;

FIG. 2 is a plan view of one form of the connector;

FIGS. 3 and 4 are sectional views on the, lines 3-3 and 4-4- of FIG. 1;

FIGS. 5 and 6 are fragmentary side elevational views of modified forms of the connector used with a tension shackle;

FIG. 7 is a view similar to FIG. 1 but including a compression shackle.

FIG. 8 is a fragmentary side elevational view showing a modified form of the connector for use with a compression shackle;

FIG. 9 is a diagrammatic view showing a conventional automobile rear spring suspension with a tension shackle;

FIG. 10 is a diagrammatic view similar to FIG. 9 showing the change in the shackle angle when the new connector is used;

FIGS. 11 and 12 are diagrammatic views showing the suspension of FIG. 10 in maximum compression and rebound, respectively;

FIG. 13 is a diagrammatic view showing the angle of a compression shackle in a conventional suspension;

FIG. 14 is a view similar to FIG. 13 showing the change in the angle of the FIG. 13 shackle when the new connector is used;

7 FIGS. 15 and 16 are diagrammatic views showing the suspension of FIG. 14 with the spring maximum com pression and rebound, respectively; and

FIG. 17 is a chart showing the stiffness rates of a fiat spring at different deflections in compression and rebound and with and without the new connector.

The automobile rear spring suspension shown in FIG. 1 comprises a leaf spring 20 having an eye 21 at its front end which is connected to a frame member 22 of the vehicle in a conventional manner by means of a bolt or pin 23. The spring is attached to the axle 24 from beneath by a clamp 25 and at its rear end has a second eye 26. The frame member is provided with a hanger 27 attached to the underside of the member and extending down and beneath the rear end of the spring. At its free end, the hanger is formed with an eye 28 receiving the bolt 29 of a shackle 30 formed by a pair of parallel plates connected by bolts at their ends. In a conventional suspension, the second shackle bolt 31 is passed through the eye 26 of the spring but the suspension illustrated includes the new connector which receives the bolt The connector comprises a plate 32 of the same width as the spring and provided near one end with a U-shaped clip 33 secured to the top of the plate by riveting or the like and provided with downwardly extending ears 33a at its ends which lie outside the edges of the plate and the spring and serve to hold the plate in alignment with the spring. Between its ends, the plate is provided with a clamp for securing it to the spring and the clamp shown includes a cross-bar 34 resting on the plate and a stirrup 35 extending beneath the spring and having its ends passing through opening in the cross-bar and threaded into nuts 36. At its rear end, the plate is bent upwardly to form an eye 37 for receiving the upper bolt of the shackle. When the connector is in place, the eye 37 of the plate lies inward from and in contact with the eye 26 on the spring and the attachment of the shackle to the plate eye changes the shackle and increases the stiifness of the spring, as will presently be explained.

Instead of employing a connector in the form of a plate secured to the top surface of the spring, the connector may have the S-forms shown in FIGS. 5 and 6. The connector 38 is intended for use with a spring 39 having an upturned eye 40 and the connector fits over the eye 40 and is secured in place thereon by a set screw 41. The connector extends inwardly over the top of eye 48 and terminatesiin an eye 38a receiving the upper bolt 42 of a tension shackle 43.

The connector 44 is for use with a spring 45 having an eye 46, the center of which lies approximately in line with the upper surface of spring 45. The connector extends about the eye 46 and is secured in place by a set screw 47. The connector terminates at its inner end in an eye 48 receiving the bolt 49 of a tension shackle 50.

The automobile rear suspension shown in FIG. 7 includes a spring 51 having an eye at its front end connected by a pin or bolt 52 to a frame member 53 of the vehicle. The spring is connected to the axle 54 by a clamp 55 and its rear end terminates in an upturned eye 56. In a conventional suspension, the rear eye 56 of the springrcceives the lower bolt 57 of a shackle 58 having an upper bolt 59 extending through openings in the frame member 53. In the suspension illustrated, the rear end of the springis connected to the shackle by a connector 60.

The connector 60 comprises a plate 61 of the width of the spring and provided withan alignment clip 621secured to thetop ,ofthe plate and having cars 62:: which project downwardly at the sides of the spring. ,Outwardly from a the clip, the plate may be formed with an upward bend 61a, beyond which is mounted a clamp having a crossbar 63 resting on top of the plate and a stirrup 64 lying beneath the spring and having ends extending upward through the cross-bar and threaded into nuts 65. Beyond the clamp, the plate 61 has an upward bend 61!) conforming to the curvature of the eye 56 and, beyond the eye 56, the plate terminates in an eye 66. In the construction shownin FIG. 7, the lower bolt 57 of the shackle passes through the eye 66.

In FIG. 9 there is diagrammatically shown a conventional automobile rear spring suspension including a tension shackle 67 connecting therear spring eye 68 to the eye of a hanger 70. Theangle between the line L which passes'through the centers of the shackle bolts, and the line S which passes through the centers ofthe spring eye 68, 71 is the shackle angle and, in an ordinary suspension of the type described with a spring under design load, theshackle angle is approximately 70. suspension of FIG. 9 is shown diagrammatically with the shackle connected at its upper end to the eye 37 of the-connector shown in FIG. 1. In this suspension, the shackle angle has been increased to approximately 181. InFIG. 11, the suspension is shown under maximum compression of approximately 4" and the shackle angle has increased to 113. In FIG. 12, the spring has been shown in maximum rebound of approximately 6" and the shackle angle is 136.

FIG. 13 diagrammatically illustrates the angle of a compression shackle 72 in a conventional rear spring suspcn sion and, ordinarily, the-angle is approximately 70. In FIG. 14, the shackle S8 is illustrated as connected to the spring 51 through the connector 60 and the shackle angle has been reduced to'42. FIGS. 15 and 16 illustrate the changes in the shackle angle of the suspension of FIGS. 7 and 14 in maximum compression of about 4" and rebound of about 6", respectively. At maximum compression, the shacklesangleincreases from 42 to 5d and, at maximum rebound, the shackle angle is approximately The chart, FIG. 17, contains four curves showing the performance of tour suspensions, which include a typical 60" spring. In two of the suspensions, a tension shackle is used and one suspension includes the shackle connector In FIG. 10, the

of the invention and the other does not. The other two suspensions include a compression shackle and, in one, the connector is used, while it is omitted from the other.

The curve A shows the changes in spring rate during compression and rebound of the spring of a conventional suspension with a tension shackle at an initial angle of 70 at zero deflection of the spring. The curve B shows similar changes in spring rate, when the suspension is modified by the use of the new connector resulting in an initial shackle angle of at zero deflection of the spring.

As shownby the curves A and B, the use of thenew connector to increase the angle of a tension shackle in a typical suspension increases the stiffness at design load or zero spring eflection and, in the suspension of which the performance is shown by the curves, the use of the connector increases the spring stifiness at zero deflection from about 112 lbs/in. to about 124 lbs/in. and produces a greater stiffness through a compression of 4". The curves show that, in each case, the spring rate increases as the spring is compressed but the change in stiffness with an increase in compression is more rapid, when the connector is used. Thus, curve A shows that the rate of the spring in the suspension without the connectoris a little lower at a deflection of l" in compression than the rate at zero deflection, after which the rate increases to a maximum of about 149 lbs/in. at 4" compression. When the same suspension is provided with the connector, the spring rate at a deflection of l in compression is greater than the rate at zero defiection, as shown by the curve B, and, from this point, the curve B risesmoresteeply than the curve A until a maximum stifiness of 200 lbs/in. is reached at 4" com pression.

In rebound, the rate of the spring of the suspension using the connector does not change greatly, while the rate of the spring ofthe conventional suspension without the connector increases. The curves A and B intersect at the point P corresponding to a 2" deflection in rebound and this indicates that, at light loads, the riding qualities of the vehicle are unchanged.

The curves C-and D illustrating the performance of a suspension with a compression shackle show that the use of the new connectorto produce a reduction in the shackle anglecauses an increase in springstittness or rate at design load with the spring at zero deflection. The spring rate with the connector is greater through a compression up to 4" and the rate of increase in stiffness in compression is greater up to a maximum at 1 /2". In rebound, thespringstiffness decreases whether or not the connector is used and, at 2" in'rebound, the stiffness is thesame for the suspension with and without the connector asshown by'the intersection of thecurves at the point P1. The riding qualities of the vehicle under light loads-are thus not substantially aitected by the use of theconnector.

It will be apparent from the above thatthe connector may be used with either a tension or compression shackle to increase the stiflness of a spring by varying the shackle angle and the connector thus serves as a means for modifying a vehicle spring suspension so that the vehicle can carry overloads without sagging. The amount and rate of change of spring stiffness can be varied by constructing the connector to produce a greater or less change in the shackle angle and a form of the connector can thus be chosen to produce varying efl ects. Best results are obtained by the use of the connector with a tension shackle, when the shackle angle is in the range from 90 to and with a compression shackle, when the angle is in the range from 40 to 60". The use of the connector provides greater vehicle stability without addingsubstantial weight and it adds capacity to a standard suspension system which would otherwise be obtainable only by the use of special heavy duty springs available only at much higher cost. With the new connector installed, a heavily loaded car may take corners weasel U at speeds, which would be unsafe, if the connector were not used, and the improved control of the car resulting from the use of the connector gives increased driving pleasure.

I claim:

1. The combination with an automobile body of a leaf spring supporting the body and having eyes at its ends for bolts, a bolt in one eye connecting the spring to the body, a shackle formed of a pair of parallel plates connected by bolts at the opposite ends of the shackle, a mounting on the body receiving one shackle bolt to connect one end of the shackle to the body, the other shackle bolt being receivable in the other eye of the spring to hold the shackle at the normal shackle angle with a corresponding spring rate, and means connecting said other shackle bolt to the spring with the shackle held at a shackle angle resulting in a spring rate higher than said first-named spring rate, the connecting means consisting essentially of a plate lying in contact with one horizontal surface of the spring and having an eye receiving said other shackle bolt, the eye of the platelying in contact with said other spring eye and offset therefrom lengthwise of the spring, and means securing the plate rigidly to the spring.

2. The combination of claim 1, in which the mounting is higher than the second eye of the spring and the shackle is under compression.

3. The combination of claim 1, in which the mounting is on a hanger attached to the body and is lower ond spring eye.

6. The combination of claim 1, in which the plate rests on top of the spring and the plate eye lies inwardly from the second spring eye.

7. The combination of claim 6, in which the plate partially encircles the second spring eye.

8. The combination of claim 6, in which the securing means is a set screw threaded through the plate and engaging the spring.

References Cited in the file of this patent UNITED STATES PATENTS 1,172,499 Stenzel Feb. 22, 1916 1,179,888 Badlat Apr. 18, 1916 1,223,705 Leymarie Apr. 24, 1917 1,277,580 Hayes Sept. 3, 1918 1,265,825 Sprague May 14, 1919 1,343,027 Beck June 8, 1920 1,404,677 Zeppengo Jan. 24, 1922 1,464,341 Rodin Aug. 7, 1923 1,569,535 Cole Jan. 12, 1926 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,022,991 February 27, 1962 Anthony F. Billard It is hereby certified that error appears in the above numbered patent req'iiring correction and that the said Letters Patent should read as corrected below.

Column l line 12, for "shackly" read shackle line 66, after "characteristics" insert resulting column 2, line 35, after "spring" insert in line 66, for "opening read openings column 3, line 1 after "shackle" insert angle Signed and sealed this 19th day of June 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents 

